A television feature called PIP allows a television viewer to view a main television program while monitoring (typically in a small "window") another PIP program. When an exciting event occurs in the PIP program, the viewer can swap the program being viewed in the main display with the program being viewed in the PIP. The problems with such a system are that the viewer cannot monitor the audio information in the PIP, and in addition the PIP occupies a portion of the main display which is quite annoying to a viewer watching on the program information in the main display.
For viewers without PIP, many will switch from a favorite channel to another channel while waiting for some event to occur on the favorite channel. It is typical, for example, for a viewer to switch back and forth between a football game and some other programming while there is little action in the football game, but many times a touchdown is missed without the viewer even knowing it.
In previously known television receiving devices aimed at solving these problems, such as that disclosed in U.S. Pat. No. 5,585,865, the televisions monitor the program content of a channel by relying on additional data which is transmitted with a television signal, such as the data received from the Extended Data Service (EDS). In this prior art television receiver a user selects a particular genre of programming that he/she would like to view such as "Sports". The EDS data is then extracted from the incoming video signals and compared to the genre selected by the viewer. If a match is found on a particular channel the television tuner is switched to this channel.
The problems associated with such a system is that it requires "program type" data, which indicates the type of program e.g."Sports" "Movie" "News" etc.), to be transmitted in addition to the video signal. The user therefore must rely on the broadcasters to agree to transmit such "program type" data. Even if there is an agreement among broadcasters to transmit this data, such a monitoring system does not permit a user to monitor data on a user defined basis and more importantly the user cannot monitor events occurring in the video signal or in the audio signal but only events occurring in the EDS data. In particular the user cannot monitor information occurring within the program such as when a favorite sports figure's name is mentioned during a program, whether it is during a sporting event or simply on the news. Similarly, it is known to detect header information in the transmitted signal for various purposes, but to date a user has been unable to define what information the user would like to detect in the video signal or audio signal.